I used to work for Walker Aviation in Ft. Lauderdale (not as a pilot) and one of their a/c was a Twin Otter, which from the TV footage shown, appears to possibly be the same a/c. As far as I'm aware and can remember, this a/c is single pilot operated.
On larger, multi-crew a/c, usually on long night sectors, it can be difficult to remain 'alert' and it is not unusual to have a 'controlled nap' whilst in your seat. This involves letting your colleague in the other seat know that you are going to be closing your eyes for 15 minutes or so. These kinds of naps are known to be beneficial and do not, in my view, affect the safe operation of the a/c. It is very rare to be able to get more than 15 minutes as the cabin crew are going to be checking in about as often as that anyway.
For those of you not familiar with this kind of flying, you can make your own simulator at home so that you can appreciate what it actually feels like. Put an armchair (not too comfortable) and a vacuum cleaner in a small darkened room. A cubby hole under the stairs is usually a suitable palce. If you have a PC, place that in there too and run a flight sim program. At about your usual bedtime sit yourself in the chair, set up a flight on autopilot in your flight sim program, preferably one of at least three hours. Turn on the vacuum cleaner and turn off any other lights and relax in the armchair. Feel free to phone a few friends who may be awake at that time of night.
If anyone would care to try this out, especially after having a break after 3-4 hours and then repeating the exercise, and get back to us here on PPRuNe and let us know if they managed to remain awake without feeling drowsy at all, it would be appreciated. If possible, repeat the exercise within 24 hours at about the same time.
The video shown on Sky News is of the pilot, asleep, being filmed from the pax cabin through doorless bulkhead to the cockpit of what appears to be a DHC6 Twotter. It was a daylight flight. As far as I remember, Walkers operated a scheduled service between their private island, Walkers Cay, Bimini, Ft. lauderdale and West Palm Beach.